A very efficient and accurate method to characterize the electromagnetic scattering from periodic arrays of two-dimensional composite cylindrical objects with internal eccentric cylindrical scatterers is presented, using the lattice sums formula and the aggregate T-matrix for cylindrical structures. The method is quite general and applies to various configurations of two-dimensional periodic arrays. The dielectric host cylinder per unit cell of the array can contain two or more eccentric cylindrical scatterers (we call them inclusions in this paper), which may be dielectric, conductor, gyrotropic medium, or their mixture with different sizes. The power reflection coefficients from one-layer or one-hundred-layered periodic arrays of composite cylinders with up to two inclusions have been numerically studied. The effect of the presence of inclusions on the properties of resonance peaks or the stopband's width will be discussed.
We present results of study of the resonance stub effect occurring in a transition from a through via hole to a stripline in a multilayer printed circuit board (PCB). This effect for via structures including ground vias is estimated by numerical simulations and measurements in the frequency band up to 20 GHz. Ways to alleviate problems in the design of interconnections embedded in multilayer PCBs due to the resonance stub effect and possible applications of the effect in microwave filtering are traced.Index Terms-Bandstop filters, interconnect circuits, multilayer printed circuit boards.
We have developed an accurate method for measuring the complex propagation constant and characteristic impedance of transmission lines embedded in multilayer printed circuit boards. It is based on mathematical error-removal schemes using two different length transmission lines and an advanced via-hole structure that minimizes coupling. Consequently, associated errors, due to discontinuities and interference can be effectively eliminated, and the frequency dependencies of the transmission line parameters can be clarified in wide frequency bandwidths. We verified the validity of this method in frequency ranges up to at least 18 GHz, by comparing the determined values with the theory derived from transverse electromagnetic (TEM) approximations.
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